1. Field of the Invention
The present invention relates to a silver halide color photographic light-sensitive material, and more particularly to a silver halide color photographic light-sensitive material which contains a high-maximum-density, high-speed and less-fogged magenta dye image-formable polymer coupler.
2. Description of the Prior Art
The formation of a color photographic image in the subtractive color process is carried out generally by color developing a silver halide photographic light-sensitive material with use of an aromatic primary amine developing agent in the presence of a cyan coupler, a magenta coupler and an yellow coupler, in which the silver halide particles of the exposed silver halide photographic light-sensitive material are reduced by the developing agent, and at the same time the produced oxidized product of the developing agent effects coupling reactions with these couplers to form a color photographic image consisting of cyan dye, magenta dye and yellow dye.
The above couplers may be contained in either the silver halide emulsion layers or a color developer liquid.
In general, in order to form an yellow dye, for example, acylacetanilide-type or benzoylmethane-type couplers are used; to form a magenta dye, pyrazolone-type, pyrazolobenzimidazole-type, cyanoacetophenone-type or indazolone-type couplers are chiefly used; and to form a cyan dye, phenol-type or naphthol-type couplers are mainly used. Those couplers to be used are required to have such various characteristics that they not only form dyes by color development but be excellent in the color developability as well as in the dispersibility and stability in the silver halide emulsion, and the dyes thus formed be stable against light, heat, moisture, etc., and have spectral absorption wavelength regions in desirable ranges.
In a multilayered color photographic light-sensitive material, in order to prevent the intermixing of the respective dyes to improve the color reproducibility, it is necessary to fix the respective couplers into the separate, appropriate layers.
There have been known various methods in the coupler nondiffusion process for this purpose.
One of these methods is the introduction of a long-chain aliphatic group into coupler molecules to prevent the diffusion of the coupler; the coupler is either rendered alkali-soluble to be added to an aqueous gelatin solution or dissolved into a high-boiling organic solvent and emulsifiedly dispersed into an aqueous gelatin solution. These couplers, however, have the drawback that they increase extremely the viscosity of the gelatin solution, or produce undesirable crystal deposits in the emulsion. And the high-boiling organic solvent, since it softens the emulsion layers, requires a large amount of gelatin, thus making it difficult to form thin emulsion layers.
On the other hand, there is a method which uses the latex of a polymer coupler that is obtained by the polymerization of a monomer coupler which is made nondiffusible and to whose molecules is introduced a polymerizable unsaturated bonding-containing group.
The polymer coupler is added in the latex form to a hydrophilic colloidal composition, and there are many methods for adding the coupler. Some of the methods are as follows: One method is such that a coupler monomer, if necessary, along with other copolymerizable components, is polymerized in the emulsion polymerization process to be directly form a latex, and the latex is then added to a silver halide emulsion; and another is such that a coupler monomer, if necessary, along with other copolymerizable components is polymerized in the solution polymerization process to thereby obtain a polymer coupler, the polymer coupler is dissolved into a solvent, and the solution is then dispersed into an aqueous gelatin solution to form a latex. The emulsion polymerization process of the former is described in U.S. Pat. Nos. 3,370,952 and 4,080,211. The process of the latter is described in, for example, U.S. Pat. No. 3,451,820. Such methods that a polymer coupler is added in the latex form to a hydrophilic colloidal composition have the following advantages over other methods:
That is, the latex-form polymer coupler can contain high-concentration coupler units and, since it contains no high-boiling solvent, permits the formation of a thinner layer, thus contributing to improvement of image sharpness. And, since it little increases the viscosity of an aqueous gelatin solution, it allows rapid, uniform emulsion coating. Further, the polymer coupler, because it is in the latex form, will in no case deteriorate the strength of the formed emulsion layer.
There are some examples of such the addition of a polymer coupler in the latex form to a silver halide emulsion. For example, U.S. Pat. Nos. 4,080,211 and 3,451,820, and British Pat. No. 1,247,688 described methods for the production of a 4-equivalent magenta polymer coupler latex; U.S. Pat. No. 3,767,412 describes cyan polymer coupler latexes; and U.S. Pat. No. 3,926,436 and West German Pat. No. 2,725,591 describe copolymer latexes with competing couplers. However, these polymer coupler latexes, although they have the aforementioned many excellent advantages, have the following questions yet to be solved for further improvements:
(1) The coupling reaction rate is so slow that no adequate dye density is obtained. PA0 (2) Undesirable fog tends to be produced in color development. PA0 (3) The solubility of the coupler monomer is so small that the polymerizability is extremely low. PA0 (4) The resulting dye image is poor in the resistance against heat and moisture.